In 1704 he resigned the office of secretary, and on 26 June 1705 was made lord justice general, retaining office till 1710. Lockhart states that though ' he pretended to favour the Royal Family [the family in exile] and the episcopal clergy, yet he never did one act in favour of any of them, excepting that when he was secretary to Queen Anne he procured an Act of Indemnity and a letter from her recommending the episcopal clergy to the Privy Council's protection; hut whether this proceeded from a desire and design of serving them is easy to determine when we consider that no sooner did Queen Anne desert the Tory party and maxims, but his Lordship turn'd as great a whig as the best of them, joined with Tweedale's party to advance the Hanoverian succession in the Parliament 1704, and was at last a zealous stickler and writer in favour of the Union' (Papers, L 74). Cromarty's able and judicious advocacy of the union is, however, his chief title to honour as a statesman, and atones for much that was foolish and inconsistent in his career. He died at New Tarbat 17 Aug. 1714, and was buried, not as he had directed beside his second wife at Wemyss, but beside his ancestors at Dingwall. Dean Swift states that 'my lord of Cromarty, after four score went to his country house in Scotland with a resolution to stay six years, and lived thriftily in order to save up money that he might spend it in London' ('Thoughts on Various Subjects,' Works, iv. 242). By his first wife, Anna, daughter of Sir James Sinclair of Mey, baronet, he had four sons: Roderick, who died young; John, who succeeded his father; Kenneth, and James. 'By his second wife, Margaret, countess of Wemyss, he had no issue.
The political career of Cromarty was, perhaps, more variable and inconsistent than that of any other Scottish statesman of his time. He began as a passionate partisan, and developed into a cautious and uncertain opportunist. Lockhart describes him as 'extremely maggotty and unsettled ' (Memoirs, p. 75), and Burnet says that he had 'great notions of virtue and religion, but they were only notions' (Own Time, p. 97). He was personally popular, had 'an extraordinary gift of pleasing and diverting conversation' (Lockhart Papers, ii. 75), and was the 'pleasantest companion in the world' (Macky, Memoirs of his Secret Services, p. 188). A portrait of Cromarty, after Sir J. Baptist Medina, 'ætatis 60, anno 1692,' is in the National Portrait Gallery of Scotland at Edinburgh. Medina's portrait has been engraved by Vanderbanck.
Cromarty retained through life varied interests outside politics. He was consulted by Sir Robert Moray [q. v.] in regard to the formation of the Royal Society of London, and contributed to its 'Transactions' the following papers: 'Remarks on the Transactions of April 1675' ('Transactions,' x. 305); 'Account of Severe Wind and Frost' (ib. x. 807); 'Observations on Natural History made in Scotland' (ib. x. 396); 'Mosses in Scotland,' in a letter to Dr. Hans Sloane, 15 Nov. 1670 (ib; xxvir. 296) An 'Account of Hirta and Rona' (islands of the Hebrides) was published in 'Miscellanea Scotica,' 1818, ii. 79. He published a large number of political pamphlets, some of which are now rare. They include
- 'Memorial for his Highness the Prince of Orange in relation to the Affairs of Scotland, together with the Address of the Presbyterian party in that Kingdom to his Highness, and some Observations on that Address by two Persons of Quality,' published anonymously, London, 1689.
- 'Parainesis Pacinca. or a Persuasive to the Union of Britain,' Edinburgh, 1702, in which he exhaustively demonstrates that ' there remains but one mode of union, viz. that of being united in one body, under one and the same head, by a perpetual identifying oneness.'
- 'A Few Brief and Modest Reflections persuading a Just Indulgence to be granted to the Episcopal Clergy and People of Scotland,' 1703.
- 'Continuation of a Few Brief and Modest Reflections. Together with a Postscript vindicating the Episcopal Doctrine of Passive Obedience,' 1703.
- 'Speech to the Parliament of Scotland, 11 July 1704' (on the reading of the queen's speech).
- 'A Letter from E. C. [Earl of Cromarty] to E. W. [Earl of Wemyss] concerning the Union, and a Second Letter on the British Union,' 1706.
- 'Letter to M. of P.'
- 'Trialogues: A Conference between Mr. Con, Mr. Pro, &c, concerning the Union,' 1706 (anonymous).
- 'Friendly Response to a Letter concerning Sir George Mackenzie's and Sir John Nisbet's Observations and Response on the Matter of the Union,' 1706.
- 'Several Proposals conducing to a Further Union of Britain,' 1711.
His other works are:
- 'A Vindication of King Robert III from the Imputation of Bastardy, by the clear Proof of Elizabeth Mure (daughter to Sir Adam Mure of Rowallan), her being the First Lawful "Wife of Robert the II, then Steward of Scotland and Earl of Strathern,' Edinburgh, 1695.
- 'Several Proposals conducing to a Further Union of Britain,' 1711.
- 'Historical Account of the Conspiracy of the Earl of Gowrie and of Robert Logan of Restalrig against James VI,' 1713.
- 'A Vindication of the Same
